THE TFD TREATMENT OF THE QUASI-PARTICLE-PHONON INTERACTION AT FINITE-TEMPERATURE

The coupling of elementary excitation modes in hot nuclei is studied. For this aim the quasiparticle-phonon nuclear model (QPM) is extended to a finite temperature by using the formalism of the thermofield dyna mics. First the energies and structures of one-phonon states are calcu lated in the thermal random phase approximation and then the thermal Q PM Hamiltonian H(QPM) is expressed in terms of thermal quasiparticles and thermal RPA-phonons. The equation for the energies taking into acc ount mixing of one- and two-thermal phonon states is derived. The expr ession of the coupling matrix element between thermal phonons is given .